Illustrates the orbits of the first 4 p… by SpecialAgent

function u(t) {

c.width=1920 // clear the canvas
for(i=0;i<9;i++)
x.fillRect(400+i*100+S(t)*300,400,50,200) // draw 50x200 rects

} // 122/140

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    u(t) is called 60 times per second.
    t: Elapsed time in seconds.
    S: Shorthand for Math.sin.
    C: Shorthand for Math.cos.
    T: Shorthand for Math.tan.
    R: Function that generates rgba-strings, usage ex.: R(255, 255, 255, 0.5)
    c: A 1920x1080 canvas.
    x: A 2D context for that canvas.

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SpecialAgent

function u(t) {

c.width^=0;r=400;A=[.4,.7,1,1.5,1,2,4,7];for(n=4;n--,q=r*A[n],d=t/A[n+4];)x.arc(r*2,r,q,1,9),x.stroke(),x.fillRect(r*2+q*C(d),r+q*S(d),9,9)

Mar 2 2017 10:55 AM UTC

}// 139/140

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Illustrates the orbits of the first 4 planets in our solar system. The distance from the sun (not shown but expected in the center) and the orbital periods are to approximate scale. Variable A holds the planetary data, positions 0-3 indicate the distance in Astronomical Units from the sun, positions 4-7 the number of days for orbital periods. These are rounded to fit into the 140 byte limit. Earth should be 3.65, but is rounded up to 4. Not perfect but a close approximation. q is the radius of each orbit (derived from the AU distance), and d is the angle of the planet on the orbital path (derived from the days per orbital period).

u/donbright

hell yeah
u/donbright

remix to show e-v orbital resonance https://www.dwitter.net/d/1811
u/donbright

i wish i could vote twice on SpecialAgent's dweet, so cool.
u/SpecialAgent

Thank you donbright :)
u/SpecialAgent

A golfed version that tunes earth's orbital period to 360 days, and speeds up the simulation: c.width^=0;r=600;for(n=4;n--,q=r*[.2,.3,.5,.75][n],d=t*2/[1,2,3.6,7][n];)x.arc(r,r,q,1,9),x.stroke(),x.fillRect(r+q*C(d),r+q*S(d),9,9)


      u(t) is called 60 times per second.
      t: elapsed time in seconds.
      c: A 1920x1080 canvas.
      x: A 2D context for that canvas.
      S: Math.sin
      C: Math.cos
      T: Math.tan
      R: Generates rgba-strings, ex.: R(255, 255, 255, 0.5)

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